- Set the Digital multi meter knob to diode measurement mode
- Place the red probe on the ground and the black probe on the measuring part/component
- If the voltage or meter shows 0.0v then its a short circuit
When performing the short-circuit test, the battery and adapter must be unplugged.
A multimeter diode measurement shows the value of the voltage drop that occurs when a current flows from the multimeter to the measurement component and the current passes through the measurement component. The voltage drop is smaller with lower resistance and larger with higher resistance. This is because a higher resistance requires a greater voltage to flow current.
A short is a state in which there is no resistance because the power (+) and ground (-) are connected directly. Therefore, measuring the short part will give a value close to 0.0 v with little voltage drop. Conversely, measuring a high-resistance component results in a higher voltage drop, resulting in a higher value. If there is no current flowing through the insulation, the diode value will be OL. (Over Limit)
capacitor:Capacitors are separated at both ends. One is connected to power and the other to ground. Measure both ends and if the diode voltage on both ends is 0V, it is a short circuit. This reaction occurs when power and ground are connected due to a short circuit inside the capacitor.
Resister:A resistor is a device that impedes/resists the flow of current but allows current to flow through it. If the resistance is a problem, the current does not flow because both ends are broken or the resistance value is wrong. If you measure both ends of a resistor as low as 10 ohms, the diode voltage will come out to 0V.
Inductor / Coil:An inductor is a device connected to the output power. There should be no short-circuit reaction as current is flowing at both ends. If the diode reading is 0.0V, then there is a short circuit in the inductor and the peripherals connected to it. An inductor is simply an element with a coil wound on it, so it does not cause a short circuit.
Diode:Diodes allow current to flow in only one direction. When measuring with a red probe to the anode (+) and a black probe to the cathode (-), a voltage between 0.2V and 0.8V is obtained. If you change the probe and measure it in the reverse direction, it is a short circuit. The measured voltage is different depending on the type of diode.
A device with two terminals can be classified as plus or minus, but for a device with three terminals, it is necessary to refer to the datasheet or circuit diagram.
MOSFET:The MOSFET has three terminals: gate, source and drain. The gate is insulated from the source and drain so that current does not flow between them. It is a short circuit when the gate is connected to ground or the diode voltage connected to the source and drain appears.
The source and drain are connected by an internal diode. When measuring with a red probe on the source side and a black probe on the drain side, the diode forward voltage is about 0.4V. If the reverse voltage is obtained by reversing the probe, it is a short circuit. Even if it is not a short circuit, the MOSFET will malfunction if the internal diode value is low.
A typical 8-pin device has 1 2 3 pins as the source, 4 pins as the gate, and the 5678 pins as the drain. There are also dual MOSFETs with two MOSFETs in one device, so you'll need to refer to a datasheet or schematic.
Integrated Chip or IC:IC chip shorts are checked by measuring peripheral devices. The capacitor is connected to the IC chip input power and the inductor is connected to the output power. If a short reaction occurs by measuring peripheral devices, there is a possibility that the IC chip is shorted. Before replacing the IC chip, you need to remove the peripherals to see if the short circuit disappears.
Note: When measuring CPU coil and GPU coils, usually we get low Ohms below 10 Ohms, this is not short in these coils, this is normal because the processor and graphics processor has got very low ohm to ground, that is why it gets low ohm.
if the GPU coils and CPU coils getting the reading of 0 Ohms or 0.0v in diode mode then its surely short of CPU or related to CPU and GPU sections.